3rd generation partnership project (3GPP) long term evolution (LTE) is an improved version of a universal mobile telecommunication system (UMTS) and is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPP LTE.
A micro cell, a femto cell, and a pico cell, etc., having a small service area can be installed in a specific location of a macro cell having a wide coverage.
Due to mobility of a user equipment (UE) represented as a mobile device, quality of a currently provided service may deteriorate or a cell capable of providing a better service may be detected. Accordingly, the UE may move to a new cell, which is called performing of the mobility of the UE.
In order to perform the mobility, the UE persistently performs measurement on a serving cell and a neighboring cell. When the measurement result satisfies a condition for performing the mobility, the UE can receive an instruction from the serving cell and can directly perform the mobility.
There may be a particular type of cell providing a service only to an access-permitted member UE. Such a cell may be, for example, a closed subscriber group (CSG) cell. When a UE performs mobility, the UE determines whether or not the UE itself is a member when a target cell is a CSG cell. Only when the UE itself is a member of the target cell, the UE may access the corresponding cell.
In the foregoing wireless communication system, in order to support mobility of a UE, predetermined type cell identification information may be reserved in order to first discriminate a particular type of cell such as the CSG cell. A network may provide the reserved cell identification information to the UE to allow the UE to perform mobility more effectively.
In the foregoing wireless communication system where the highest priority is allocated to a frequency on which a predetermined type cell is operating, a measurement result reported by a UE may be very limited. In this case, a network is not able to properly optimize a performance of the network in basis of the measurement result. Therefore, it is needed that a priority is changeably applied to a serving frequency in a measurement process.